A t-private k-database information retrieval scheme

Abstract

A private information retrieval scheme enables a user to privately recover an item from a public accessible database. In this paper we present a private information retrieval scheme for k replicated databases. The scheme is information-theoretic secure for coalitions of databases of size t≤k-1. It improves the communication complexity of the scheme described in [Ishai and Kushilevitz (1999) Proc 31st Annu ACM Symp Theory Comput pp 79–88] for coalitions of size $\tfrac{k} {2} \leqslant t \leqslant k - 1$.